The Speech Chain - Columbia University

1 X PrefaceOf course, the elements of the Speech Chain have not changedsince the original publication of our book. Indeed, the physics ofsound and the physiology of Speech and hearing remain unchangedsince the earliest humans. On the other hand, great changes haveoccurred during the last three decades in our understanding of thesubject and in the technology we use to perform research and to buildcommercial devices to transmit, produce, or recognize of the driving forces behind these advances has been theavailability of powerful yet affordable computer technology.

2 Digitaltechniques have become pervasive in our society. Consumer products,medical equipment, and manufacturing automation often depend ondigital technology, as do hearing aids, Speech recognizers and synthe-sizers, and would like to thank the many people who have shared theirideas with us and who have been kind enough to read drafts of part orall of this book, including Jont Allen, Bishnu Atal, David Berkley,Nikel Jayant, Peter Ladefoged, Ilse Lehiste, Steve Levinson, MikeNoll, David Pisoni, Larry Rabiner, Catherine Ringen.

3 Alex Rud-nicky, Manfred Schroeder, Juergen Schroeter, and Bruce Smith. Theyhelped us greatly to focus on the improvements that we believe makethis edition more informative than its predecessors. We would alsolike to thank Julia Hirschberg and Thrasos Pappas for their kind helpin preparing some of the Speech spectrograms included in the DenesElliot PinsonThe Speech Chaine usually take for granted our ability to produce andunderstand Speech and give little thought to its nature and function,just as we are not particularly aware of the action of our hearts,brains, or other essential organs.

4 It is not surprising, therefore, thatmany people overlook the great influence of Speech on the develop-ment and functioning of human human beings live together, they develop a system oftalking to each other; even people in the most isolated societies usespeech. Speech , in fact, is one of the few basic abilities-tool makingis another-that set us apart from other animals and are closelyconnected with our ability to think is Speech so important? One reason is that the developmentof human culture is made possible- to a great extent-by ourability to share experiences, to exchange ideas and to transmit knowl-edge from one generation to another; in other words, our ability tocommunicate with others.

5 We can communicate with each other in2 CHAPTER I The Speech ChainThe Speech Chain 3many ways. The smoke signals of the Apache Indian, the starter spistol in a loo-yard dash, the sign language used by deaf people, theMorse Code and various systems of writing are just a few examples ofthe many different systems of communication that have evolved tomeet special needs. Unquestionably, however, Speech is the systemthat human societies have found, under most circumstances, to be farmore efficient and convenient than any may think that writing is a more important means ofcommunication than Speech .

6 After all, the written word and theoutput of printing pressesappear to be more efficient and moredurable means of transmitting information. Yet, no matter howmany books and newspapers are printed, the amount of information*exchanged by Speech is still greater. The use of books and prmtedmatter has expanded greatly in our society, but so has the use oftelephones, radio, and short, human society relies heavily on the free and easyinterchange of ideas among its members and, for many reasons, wehave found Speech to be our most convenient form of its constant use as a tool essential to daily living.

7 Speechhas developed into a highly efficient system for the exchange of evenour most complex is a system particularly suitable forwidespread use under the ever changing and varied conditions of is suitable because it remains functionally unaffected by the manydifferent voices, speaking habits, dialects and accents of the millionswho use a common language. And it is suitable for widespread usebecause Speech -to a surprising extent-is invulnerable to severenoise, distortion and is well worth careful study.

8 It is worthwhile because thestudy of Speech provides useful insights into the nature and history ofhuman civilization. It is worthwhile for the communications engi-neer because a better understanding of the Speech mechanism helps indeveloping better and more eficient communication systems. It isworthwhile for all of us because we depend on Speech so heavily forcommunicating with study of Speech is also important for the development ofhuman communication with machines. We all use automatons, likepush-button telephone-answering machines and automatic elevators,which either receive instructions from us or report back to us on theiroperations.

9 Frequently, they do both, like the computers used soextensively in our society; their operation increasingly relies on fre-quent, fast, and convenient exchanges of information with users. Indesigning communication systems or languages to link user andmachine, it should prove worthwhile to have a firm understanding ofspeech, that system of person-to-person communication whose devel-opment is based on the experience of many most people consider Speech , they think only in terms ofmoving lips and tongue.

10 A few others, who have found out aboutsound waves, perhaps in the course of building or using stereosystems, will also associate certain kinds of sound waves with reality, Speech is a far more complex process, involving many morelevels of human activity, than such a simple approach would convenient way of examining what happens during Speech is totake the simple situation of two people talking to each other. Forexample, you as the speaker, want to transmit information to anotherperson, the listener.